Parents Doris and Donald fisher return to The Forbes 400 as the art market swells. Couple's large contemporary collection, featuring pieces by Chuck Close, Richard Serra and Alexander Calder, said to be worth more than $1 billion. Duo founded music-and-jeans store Gap in San Francisco 1969; public 1976. Handed control of company—and nearly half their stock—to sons John, Robert and William in 2004; shares down 20% since. Company plans to close or downsize some of its 3,100 stores, open new ones; annual sales down 2.5% to $15.8 billion since 2004. Introduced universal Web site for its 4 brands: Gap, Old Navy, Banana Republic, Piperlime. Expanding to Russia. Robert stepped down as interim chief executive last August; still on board.